/*
 * Copyright 2019 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "modules/skottie/src/effects/Effects.h"

#include "include/core/SkCanvas.h"
#include "include/core/SkPicture.h"
#include "include/core/SkPictureRecorder.h"
#include "include/core/SkShader.h"
#include "include/effects/SkGradientShader.h"
#include "include/private/base/SkTPin.h"
#include "modules/skottie/src/Adapter.h"
#include "modules/skottie/src/SkottieValue.h"
#include "modules/sksg/include/SkSGRenderNode.h"
#include "src/utils/SkJSON.h"

#include <cmath>

namespace skottie {
namespace internal {
namespace {
// AE motion tile effect semantics
// (https://helpx.adobe.com/after-effects/using/stylize-effects.html#motion_tile_effect):
//
//   - the full content of the layer is mapped to a tile: tile_center, tile_width, tile_height
//
//   - tiles are repeated in both dimensions to fill the output area: output_width, output_height
//
//   - tiling mode is either kRepeat (default) or kMirror (when mirror_edges == true)
//
//   - for a non-zero phase, alternating vertical columns (every other column) are offset by
//     the specified amount
//
//   - when horizontal_phase is true, the phase is applied to horizontal rows instead of columns
//
class TileRenderNode final : public sksg::CustomRenderNode {
public:
    TileRenderNode(const SkSize &size, sk_sp<sksg::RenderNode> layer)
        : INHERITED({ std::move(layer) }), fLayerSize(size)
    {}

    SG_ATTRIBUTE(TileCenter, SkPoint, fTileCenter)
    SG_ATTRIBUTE(TileWidth, SkScalar, fTileW)
    SG_ATTRIBUTE(TileHeight, SkScalar, fTileH)
    SG_ATTRIBUTE(OutputWidth, SkScalar, fOutputW)
    SG_ATTRIBUTE(OutputHeight, SkScalar, fOutputH)
    SG_ATTRIBUTE(Phase, SkScalar, fPhase)
    SG_ATTRIBUTE(MirrorEdges, bool, fMirrorEdges)
    SG_ATTRIBUTE(HorizontalPhase, bool, fHorizontalPhase)

protected:
    const RenderNode *onNodeAt(const SkPoint &) const override
    {
        return nullptr;
    } // no hit-testing

    SkRect onRevalidate(sksg::InvalidationController *ic, const SkMatrix &ctm) override
    {
        // Re-record the layer picture if needed.
        if (!fLayerPicture || this->hasChildrenInval()) {
            SkASSERT(this->children().size() == 1ul);
            const auto &layer = this->children()[0];

            layer->revalidate(ic, ctm);

            SkPictureRecorder recorder;
            layer->render(recorder.beginRecording(fLayerSize.width(), fLayerSize.height()));
            fLayerPicture = recorder.finishRecordingAsPicture();
        }

        // tileW and tileH use layer size percentage units.
        const auto tileW = SkTPin(fTileW, 0.0f, 100.0f) * 0.01f * fLayerSize.width(),
                   tileH = SkTPin(fTileH, 0.0f, 100.0f) * 0.01f * fLayerSize.height();
        const auto tile_size = SkSize::Make(std::max(tileW, 1.0f), std::max(tileH, 1.0f));
        const auto tile = SkRect::MakeXYWH(fTileCenter.fX - 0.5f * tile_size.width(),
            fTileCenter.fY - 0.5f * tile_size.height(), tile_size.width(), tile_size.height());

        const auto layerShaderMatrix =
            SkMatrix::RectToRect(SkRect::MakeWH(fLayerSize.width(), fLayerSize.height()), tile);

        const auto tm = fMirrorEdges ? SkTileMode::kMirror : SkTileMode::kRepeat;
        auto layer_shader = fLayerPicture->makeShader(tm, tm, SkFilterMode::kLinear, &layerShaderMatrix, nullptr);

        if (fPhase && layer_shader && tile.isFinite()) {
            // To implement AE phase semantics, we construct a mask shader for the pass-through
            // rows/columns.  We then draw the layer content through this mask, and then again
            // through the inverse mask with a phase shift.
            const auto phase_vec =
                fHorizontalPhase ? SkVector::Make(tile.width(), 0) : SkVector::Make(0, tile.height());
            const auto phase_shift = SkVector::Make(phase_vec.fX, phase_vec.fY) * std::fmod(fPhase * (1 / 360.0f), 1);
            const auto phase_shader_matrix = SkMatrix::Translate(phase_shift.x(), phase_shift.y());

            // The mask is generated using a step gradient shader, spanning 2 x tile width/height,
            // and perpendicular to the phase vector.
            static constexpr SkColor colors[] = { 0xffffffff, 0x00000000 };
            static constexpr SkScalar   pos[] = {       0.5f,       0.5f };

            const SkPoint pts[] = {{ tile.x(), tile.y() },
                                   { tile.x() + 2 * (tile.width()  - phase_vec.fX),
                                     tile.y() + 2 * (tile.height() - phase_vec.fY) }};

            auto mask_shader = SkGradientShader::MakeLinear(pts, colors, pos, std::size(colors), SkTileMode::kRepeat);

            // First drawing pass: in-place masked layer content.
            fMainPassShader = SkShaders::Blend(SkBlendMode::kSrcIn, mask_shader, layer_shader);
            // Second pass: phased-shifted layer content, with an inverse mask.
            fPhasePassShader = SkShaders::Blend(SkBlendMode::kSrcOut, mask_shader, layer_shader)
                                   ->makeWithLocalMatrix(phase_shader_matrix);
        } else {
            fMainPassShader = std::move(layer_shader);
            fPhasePassShader = nullptr;
        }

        // outputW and outputH also use layer size percentage units.
        const auto outputW = fOutputW * 0.01f * fLayerSize.width(), outputH = fOutputH * 0.01f * fLayerSize.height();

        return SkRect::MakeXYWH((fLayerSize.width() - outputW) * 0.5f, (fLayerSize.height() - outputH) * 0.5f, outputW,
            outputH);
    }

    void onRender(SkCanvas *canvas, const RenderContext *ctx) const override
    {
        // AE allow one of the tile dimensions to collapse, but not both.
        if (this->bounds().isEmpty() || (fTileW <= 0 && fTileH <= 0)) {
            return;
        }

        SkPaint paint;
        paint.setAntiAlias(true);

        if (ctx) {
            // apply any pending paint effects via the shader paint
            ctx->modulatePaint(canvas->getLocalToDeviceAs3x3(), &paint);
        }

        paint.setShader(fMainPassShader);
        canvas->drawRect(this->bounds(), paint);

        if (fPhasePassShader) {
            paint.setShader(fPhasePassShader);
            canvas->drawRect(this->bounds(), paint);
        }
    }

private:
    const SkSize fLayerSize;

    SkPoint fTileCenter = { 0, 0 };
    SkScalar fTileW = 1, fTileH = 1, fOutputW = 1, fOutputH = 1, fPhase = 0;
    bool fMirrorEdges = false;
    bool fHorizontalPhase = false;

    // These are computed/cached on revalidation.
    sk_sp<SkPicture> fLayerPicture;  // cached picture for layer content
    sk_sp<SkShader> fMainPassShader, // shader for the main tile(s)
        fPhasePassShader;            // shader for the phased tile(s)

    using INHERITED = sksg::CustomRenderNode;
};

class MotionTileAdapter final : public DiscardableAdapterBase<MotionTileAdapter, TileRenderNode> {
public:
    MotionTileAdapter(const skjson::ArrayValue &jprops, sk_sp<sksg::RenderNode> layer, const AnimationBuilder &abuilder,
        const SkSize &layer_size)
        : INHERITED(sk_make_sp<TileRenderNode>(layer_size, std::move(layer)))
    {
        enum : size_t {
            kTileCenter_Index = 0,
            kTileWidth_Index = 1,
            kTileHeight_Index = 2,
            kOutputWidth_Index = 3,
            kOutputHeight_Index = 4,
            kMirrorEdges_Index = 5,
            kPhase_Index = 6,
            kHorizontalPhaseShift_Index = 7,
        };

        EffectBinder(jprops, abuilder, this)
            .bind(kTileCenter_Index, fTileCenter)
            .bind(kTileWidth_Index, fTileW)
            .bind(kTileHeight_Index, fTileH)
            .bind(kOutputWidth_Index, fOutputW)
            .bind(kOutputHeight_Index, fOutputH)
            .bind(kMirrorEdges_Index, fMirrorEdges)
            .bind(kPhase_Index, fPhase)
            .bind(kHorizontalPhaseShift_Index, fHorizontalPhase);
    }

private:
    void onSync() override
    {
        const auto &tiler = this->node();

        tiler->setTileCenter({ fTileCenter.x, fTileCenter.y });
        tiler->setTileWidth(fTileW);
        tiler->setTileHeight(fTileH);
        tiler->setOutputWidth(fOutputW);
        tiler->setOutputHeight(fOutputH);
        tiler->setPhase(fPhase);
        tiler->setMirrorEdges(SkToBool(fMirrorEdges));
        tiler->setHorizontalPhase(SkToBool(fHorizontalPhase));
    }

    Vec2Value fTileCenter = { 0, 0 };
    ScalarValue fTileW = 1, fTileH = 1, fOutputW = 1, fOutputH = 1, fMirrorEdges = 0, fPhase = 0, fHorizontalPhase = 0;

    using INHERITED = DiscardableAdapterBase<MotionTileAdapter, TileRenderNode>;
};
} // namespace

sk_sp<sksg::RenderNode> EffectBuilder::attachMotionTileEffect(const skjson::ArrayValue &jprops,
    sk_sp<sksg::RenderNode> layer) const
{
    return fBuilder->attachDiscardableAdapter<MotionTileAdapter>(jprops, std::move(layer), *fBuilder, fLayerSize);
}
} // namespace internal
} // namespace skottie
